How to Replace a Thermostat on Ford Cars

by Contributing Writer

A Ford car thermostat operates to prevent the flow of antifreeze from the radiator to the engine to allow the engine to quickly warm up. Once the engine has reached its normal operating temperature, the thermostat opens, thereby allowing the antifreeze from the engine to circulate though the engine. Over time, a thermostat can stick in one position. If the thermostat is stuck in the open position, it will take the engine longer to reach normal operating temperature. If the thermostat is stuck in the closed position, the fluid within the radiator will be prevented from entering the engine, and will result in an engine which quickly overheats, particularly if the Ford car is used over off-road terrain. Thankfully, replacing a Ford car thermostat is a straightforward task.

Under The Hood:

 How to Replace a Thermostat on a Ford Ranger

Park your Ranger on level ground in an area free of distractions. Disconnect your negative battery cable and let the engine cool off for at least 30 minutes.

Remove the engine brush guard from underneath the engine bay (if equipped) to access the radiator drain plug. Remove the drain plug and let the engine coolant completely drain into the pain. Keep the coolant away from children and animals. It is highly toxic.

Remove the wiring harness from the rear of the thermostat (located behind the radiator). Use the socket wrench to remove the thermostat and its gasket. Wipe the are clean with a rag and discard the old gasket.

Mount the new thermostat and gasket to the radiator with the torque wrench. The proper torque level for the Ford Ranger is 89 inch-pounds for four-cylinders and 4.0 L V6 engines. The proper level for the 3.0 L V6 engine is between 15 and 22 foot-pounds.

Replace the drain plug, wiring harness and engine coolant. Reconnect the negative battery cable and start the engine to check for leaks. If there are no leaks, replace the engine brush guard.

Items you will need

  • Pliers

  • Socket wrench aet

  • Torque wrench

  • Drain pan

  • Replacement thermostat

  • Replacement thermostat gasket

  • Funnel

 How to Change the Thermostat in a Ford Focus

Make sure the engine of your Ford Focus is cool. Use jack and jack stands or wheel ramps to raise the front of your Focus. Turn radiator cap about 1/4-turn to release pressure in the cooling system. Remove cap when hissing stops, indicating pressure is relieved.

Locate radiator draincock on the passenger-side of the bottom of the radiator, facing the rear of the Focus. Attach a hose to the plug if desired to minimize coolant spillage. Loosen the plug to drain coolant into a suitable container. Reuse coolant if relatively new and clean.

Press the retaining clip on the bottom of the coilpack wiring harness upwards while pulling the plug toward you to unplug the harness. Use a 10mm open-end wrench and a 13mm socket to remove the bracket holding the exhaust gas recirculation (EGR) tube. Push EGR tube down to access thermostat housing.

Use pliers to loosen the clip at the engine-end of the upper radiator hose where it meets the thermostat housing. Pull the hose off the housing. Take out two bolts holding housing cover and remove cover.

Note the position of the old thermostat. Pull out the old thermostat and seat new thermostat into thermostat housing in the same position. Clean any residue from inside the housing cover. Place new gasket over the thermostat and replace housing cover.

Reattach radiator hose, EGR tube and bracket and the coilpack wiring harness. Refill the radiator with reserve or new coolant. Start your Focus and allow the engine to warm up. Check for leaks.

Items you will need

  • Jack and jack stands or wheel ramps

  • Drain hose (optional)

  • Container

  • 10mm open-end wrench

  • 13mm socket

  • Pliers

  • Thermostat and gasket

 How to Change the Thermostat in a Ford Taurus

Turn the drain valve at the bottom of the radiator counterclockwise to drain the coolant from your Ford Taurus into a suitable container. Depending on the size of the container, it may be necessary to lift the front end of your Taurus with a jack and lower it onto jack stands, or use wheel ramps.

Follow the upper radiator hose to the point where it meets the thermostat housing at the front of the intake manifold. Loosen the hose clamp and pull the radiator hose off the water connection on the thermostat housing.

Take out the two bolts on the thermostat housing cover with a 13mm socket or wrench and remove the cover. Clean any old gasket residue from the inside of the thermostat housing cover. Pull out the old thermostat.

Insert the new thermostat into the thermostat housing with the spring-side facing into the engine. Install the new thermostat gasket. Use a spray adhesive to hold the gasket in place, if desired.

Reinstall the thermostat housing cover. Tighten the bolts to 89-124 in. lbs. Reattach the upper radiator hose to the thermostat housing. Make sure the drain valve on the radiator is closed.

Fill the radiator with new or reserve coolant. Start your Ford Taurus and allow it to warm up to its normal operating temperature. Check hoses and connections for leaks and tighten hose clamps to stop any leaks, if necessary. Add more coolant as needed.

Items you will need

  • Container

  • Jack and jack stands or wheel ramps (if needed)

  • Screwdriver

  • 13mm socket or wrench

  • Thermostat and gasket

 How to Change the Thermostat on a Hyundai Accent

Open the hood of your Accent and allow the engine to cool.

Place a clean drain pan underneath the radiator. Turn the radiator drain valve in a counterclockwise direction with a pair of pliers. Allow the coolant to drain completely from the radiator into the pan. Close the drain valve in a clockwise direction and tighten with pliers. Do not over-tighten the valve as the plastic radiator tank can be damaged.

Locate the upper radiator hose and trace it from the top of the radiator to the thermostat housing on the engine block. Loosen the hose clamp on the upper radiator hose at the thermostat with a Philips screwdriver. Pull the hose from the thermostat using a twisting motion to release it from the housing if necessary.

Remove the two thermostat housing retaining bolts with a socket and ratchet wrench turned in a counterclockwise direction. Place the bolts aside. Pry the housing up carefully with a flat blade screwdriver. Now pry the thermostat out of the housing, paying attention to whether the cone is facing upwards or downwards.

Clean the thermostat mounting surface, as well as the thermostat housing, of old gasket residue with a gasket scraper. Place a new thermostat gasket over the mounting surface on the engine block. Place a new thermostat into the block in the same orientation as the old thermostat. Place the thermostat housing back over thermostat and tighten the retaining bolts with a socket and ratchet.

Open the radiator cap and place a funnel in the opening. Slowly pour the coolant from the drain pan into the radiator. Remove the funnel and replace the radiator cap. Close the hood.

Check the coolant after the car has been driven once and allowed to cool down. Add Coolant to bring the level up to the full mark, if necessary.

Items you will need

  • Drain pan

  • Pliers

  • Philips screwdriver

  • Metric socket set

  • Ratchet wrench

  • Flat blade screwdriver

  • Gasket scraper

  • Thermostat gasket

  • Replacement thermostat

  • Funnel

 How to Change the Thermostat in a Ford Explorer

Drain the coolant from your Explorer into an adequate container by opening the drain plug at the bottom of the radiator. Save the coolant for reuse if it is relatively new and clean.

Remove the negative battery cable from the battery if your Explorer has a 2.9-, 3.0-, 4.0- or 5.0-liter engine. This step is not necessary for 2.3- and 2.5-liter engines.

Follow the upper radiator hose to the front driver's side of the intake manifold, where it meets the engine. This is where the thermostat housing on your Ford Explorer is located. If necessary, remove the air cleaner duct for easy access to the housing.

Loosen the clip on the end of the radiator hose and pull the hose off the thermostat housing. Use a 10mm wrench or socket to remove the two retaining bolts on the thermostat housing cover. Remove the cover.

Note the position of the thermostat before removal. Pull out the old thermostat. Seat the new thermostat inside the housing in the same position as the old one, spring-side facing into the engine. Install new gasket over the thermostat.

Reattach the thermostat housing cover and the radiator hose. Reinstall the air cleaner duct if removed earlier. Fill the radiator with reserve or new coolant. Start your Explorer and run with the heater blowing until the engine gets warm. Check for leaks.

Items you will need

  • Container

  • Screwdriver

  • 10mm wrench or socket

  • Thermostat and gasket

 How to Change a Thermostat in a Ford Expedition

Remove the Thermostat

Put a small drain pan directly underneath the radiator drain valve.

Open the radiator drain valve, using a pair of slip joint pliers if necessary and remove at least two quarts of coolant.

Close the radiator drain valve.

Take the upper radiator hose off the thermostat housing on the side of the engine. Depending on the type of clamp used on your particular vehicle, you may use rib joint pliers or ratchet and socket to remove the clamp.

Disconnect the upper mounting bracket holding the power steering reservoir in place. On some Expedition models, this is necessary to gain access to the thermostat housing.

Remove any other hoses attached to the thermostat housing if you have a 5.4L engine model. Use pliers or a ratchet and socket to disconnect the hoses.

Unscrew the two mounting bolts from the thermostat housing using a ratchet, ratchet extension and socket.

Lift the thermostat housing and thermostat unit. Discard the thermostat O-ring.

Install the Thermostat

Install the new thermostat in place, along with a new O-ring. Make sure the thermostat spring points towards the engine.

Set the thermostat housing in place and start the two mounting bolts by hands. This will prevent damage to the threads.

Tighten the two thermostat housing mounting bolts using the ratchet and socket.

Connect the upper mounting bracket that holds the power steering reservoir in place if you had to disconnect it.

Hook the upper radiator hose to the thermostat housing and tighten the clamp using the rib joint pliers or ratchet and socket.

Connect any other hoses you disconnected from the thermostat housing if you have a 5.4L engine model.

Refill the Cooling System

Add 50 percent water and 50 percent anti-freeze to the cooling system. Pour the coolant through the radiator neck using a funnel, if necessary, and make sure the coolant reservoir level is between the "low" and "full" marks.

Turn on the engine and let it idle for about four minutes to bring the engine to operating temperature.

Check the coolant reservoir and add more coolant to bring the level between the "low" and "full" marks if necessary.

Turn off the engine.

Items you will need

  • Drain pan

  • Slip joint pliers

  • Ratchet and socket

  • Ratchet extension

  • Thermostat O-ring

  • Anti-freeze

 How to Change the Thermostat in a Ford F-150

Drain about half the coolant from the cooling system. Store the coolant in a sealable container.

Disconnect the upper radiator hose. Loosen and remove the bolts, then take out the water outlet connection.

Lift out the thermostat and the paper gasket, which is part of the assembly. Discard the used gasket.

Set the new thermostat in place with a new gasket. Note that the thermostat is indexed and must be correctly positioned.

Connect the water outlet adapter and secure it with the bolts. Tighten the bolts to 80 inch pounds. Reconnect the upper radiator hose.

Refill the coolant system to the proper levels with the recommended coolant. Start the engine and allow it to run for several minutes. Check for leaks and make the necessary adjustments. Add coolant as needed.

Items you will need

  • Mechanic's toolset, including a full socket set, wrenches and screwdrivers

  • Replacement thermostat, new or rebuilt

  • New gasket for thermostat

 How to Replace the Thermostat in a Ford Explorer

Place the drain pan under the drain bolt on the radiator. Loosen the drain bolt and allow the radiator fluid to drain. If the drain pan is clean, you can reuse the antifreeze.

Loosen the hose clamps on the upper radiator hose using a socket, screwdriver or pliers, depending on the type of hose clamp on the hose. Pull the hose off the radiator and thermostat housing. If the air filter intake hose is in the way, loosen the clamps and remove the intake hose (on some engines).

Unbolt the two bolts in the thermostat housings. Pry the thermostat housing off the engine block. Pull the thermostat out of the housing. Remove the old gasket and discard. Slide the new thermostat into the housing the same way the old one came out. Install the new O-ring seal in the housing. Coat the housing with a thin layer of silicone gasket maker. Allow the gasket maker to dry.

Slide the bolts into the thermostat housing, then line the bolts up to the bolt holes on the block. Slide the housing down the bolts until it touches the block. Turn the bolts in by hand to get them started. Tighten the bolts to 89 inch-pounds of torque.

Reinstall the upper radiator hose. Tighten the radiator drain plug. Fill the cooling system. Start the engine with the radiator cap off. Allow the engine to come up to operating temperature. Look for leaks. Watch the level of the water in the radiator. Fill as needed.

Items you will need

  • Drain pan

  • Set of sockets

  • Screwdriver

  • Pliers

  • Silicone gasket maker

  • Torque wrench

 How to Change the Thermostat in a 1998 Ford Explorer

Place the drain pan beneath the engine, below the thermostat housing. Locate the thermostat housing by following the upper radiator hose from the radiator to the housing.

Use the socket set to loosen the hose clamp on the upper radiator hose and then pull the hose off the thermostat housing by hand. Aim the hose down toward the drip pan to catch any coolant that may escape.

Use the socket set to remove the two bolts that hold the thermostat housing to the top of the engine. Lift the housing off by hand. Inspect it to make sure it has no signs of corrosion; set it aside. If there is any corrosion, you will need to replace the housing.

Pull the thermostat out of the well in the top of the engine. If it is stuck, you can use the pocket screwdriver to lift it out. Either way, it should come out easily. Note how the thermostat was positioned and oriented in the well for reference during installation.

Install the new O-ring seal around the base of the new thermostat, if it is not already present. (Some come attached in the packaging while others have the O-ring loose in the bag the thermostat is sold in.) Make sure it is properly seated on the thermostat flange. Compare it to the old thermostat for reference. The thermostat on your Ford Explorer does not have a gasket as the O-ring performs the same function, so there is no need for adhesive.

Place the new thermostat in the well, with the spring facing down into the engine. Make sure it is seated correctly. Reinstall the thermostat housing and upper radiator hose in reverse of how they were removed. If you lost any coolant in Step 2, replace it now with a 50/50 mixture of coolant and distilled water.

Items you will need

  • Drain pan

  • Socket set

  • Pocket screwdriver

  • Replacement thermostat

  • Thermostat housing (optional)

  • Coolant (optional)

  • Distilled water (optional)

 How to Change the Thermostat on an F250

Locate the thermostat by following the upper radiator hose from the F250's radiator to the connection at the intake manifold on the top of the engine. The hose is clamped to the thermostat housing.

Remove the hose from the thermostat housing by prying the clamp off with a pair of pliers and by pulling off the hose.

Remove the two bolts that secure the thermostat housing to the intake manifold. Lift the housing off the intake to expose the thermostat.

Lift the thermostat out of the intake and discard it.

Scrape the surface of the intake and the bottom of the thermostat housing with a metal scraper. Wipe the surface of the intake manifold with a towel.

Place the new thermostat into the intake manifold. The end of the thermostat with the spring goes into the intake manifold while the end with the valve is covered by the housing.

Place the thermostat gasket onto the surface of the intake manifold, place the housing on top of the gasket and secure both with the bolts.

Place the hose back onto the intake manifold and secure it with the clamp.

Items you will need

  • Pliers

  • Socket set

  • Towel

 How to Replace the Thermostat in a 2001 Ford Focus

Lift the hood and prop it open. Follow the upper radiator hose to the thermostat housing. The thermostat housing is attached with three bolts.

Unscrew the three bolts with a socket wrench. Pull the top of the housing off.

Lift the thermostat out of the housing. The thermostat rests at the bottom of the housing.

Remove any gasket material off the mating surfaces of the housing. Scrape off the remnants of the old gasket with a razor scraper.

Insert the spring end of the thermostat in the housing.

Lay the new gasket around the mating surface of the stationary part of the housing. Place the cover on top and secure it with the three bolts.

Tighten the three bolts with a socket wrench. This will create a seal to prevent leaking in the future.

Twist the radiator cap off. Pour in coolant to the radiator until the level is full.

Start the Focus and allow it to idle. Once the car is warmed up, the coolant level will go down. Pour in additional coolant until the level is full. Tighten the radiator cap.

Turn the engine off and close the hood.

Items you will need

  • Socket set

  • Socket wrench

  • Razor scraper

  • 1 gallon pre-mixed coolant

 How to Change a Thermostat in a Ford Bronco

Remove the radiator cap located on the top of the radiator by turning the cap in a counterclockwise direction.

Turn the draincock located on the bottom of the radiator to drain the fluid from the radiator. The draincock faces the engine and is located on the driver's side of the radiator. Use a wrench to remove the draincock by turning it in a counterclockwise direction.

Remove the upper radiator hose from the radiator and the thermostat housing. The radiator hose is held into place with two hose clamps, one on each end of the radiator hose. To release the clamps, turn the screw located on the clamp in a counterclockwise direction with a flathead screwdriver. Pull the upper radiator hose away from the radiator and the thermostat housing.

Remove the water pump hose from the thermostat housing. The water pump hose is attached to the thermostat housing with a single hose clamp. Release the clamp in the same manner described in step 3, then pull the hose away from the thermostat housing.

Remove the thermostat housing from the intake manifold to reveal the thermostat. The thermostat housing is attached to the intake manifold with two bolts. Remove the bolts by turning them in a counterclockwise direction with a wrench, then pull the thermostat housing away from the intake manifold to remove it.

Remove the thermostat from the intake manifold. The thermostat can simply be pulled out of the intake manifold.

Insert the new thermostat into the intake manifold. Note that one side of the thermostat has a large spring. This spring must face away from the intake manifold when installed.

Reinstall the thermostat housing. Coat both sides of a new thermostat housing gasket with gasket sealer. Rest the gasket onto the mating surface of the thermostat housing.

Ensure that the gasket's holes align with the holes on the thermostat housing. Place the thermostat housing over the thermostat then insert the two thermostat housing bolts through the housing and into the intake manifold. Secure the housing to the intake manifold by turning these two bolts in a clockwise direction with a wrench to tighten them.

Attach the water pump hose to the thermostat housing by first sliding the hose over its port on the housing. Slide the hose clamp to the end of the hose, then tighten the clamp by turning the clamp's screw in a clockwise direction with a flathead screwdriver.

Attach the radiator hose to the thermostat housing and to the radiator. Secure both ends of the radiator hose in the same manner described in step 9.

Insert the radiator's draincock into the radiator and turn the draincock in a clockwise direction with a wrench to secure it to the radiator.

Fill the radiator with new antifreeze, then attach the radiator cap to the radiator by turning the cap in a clockwise direction.

Allow at least two hours to pass before starting the engine to permit the gasket sealer to set.

Items you will need

  • Wrench

  • Flathead screwdriver

  • Thermostat housing gasket

  • Gasket sealer

  • Antifreeze

 How to Replace the Thermostat in a 1998 Ford Escort

Locate the thermostat housing by tracing the radiator hose to the location on the the intake manifold where it connects. The component the hose connects to is the thermostat housing.

Remove the radiator hose from the housing by loosening the band clamp that holds the hose onto the housing. Push the clamp farther onto the hose to prevent losing it while changing the thermostat. Pull the hose off of the housing and push it off to the side. Plug the hole in the radiator hose with a shop towel to prevent fluid from leaking onto the engine.

Remove the two bolts that hold the thermostat housing to the intake manifold of the Escort. These bolts will be used again so they should not be discarded. Once the bolts are removed, the thermostat housing can be lifted off of the intake manifold.

Remove the old paper gasket that was sandwiched between the housing and the manifold. Pull the old thermostat out of the intake. The thermostat sits on a machined lip inside of the intake and is not bolted into place.

Place RTV gasket maker on the machined surface of the intake manifold where the old gasket was. Allow 5 minutes for the RTV gasket maker to "skin" over or firm up.

Place the new thermostat into the intake manifold. Pay attention to the top end. This end must protrude from the intake manifold or the thermostat will not work properly.

Place the thermostat housing onto the intake manifold and bolt it back into place using the old bolts. You'll notice some RTV gasket maker squeeze out. This is normal and should not be removed. It will assist in the sealing process.

Pull the shop towel out of the radiator hose and reconnect it to the housing with the band clamp. The clamp should be very tight to prevent leaking.

Items you will need

  • Replacement thermostat

  • RTV gasket maker

  • Wrench

  • Screwdriver

 How to Replace the Thermostat on a 1997 Ford Taurus

Locate the upper radiator hose and trace it to the intake manifold that is located on the top of the engine on a Ford Taurus. The housing that the hose is connected to is the housing that has the thermostat inside of it.

Remove the band clamp that connects the radiator hose to the thermostat housing with a Phillips screw driver. Once the clamp is loosened the hose can be pulled off of the housing.

Remove the bolts that hold the thermostat housing to the intake manifold with a box wrench. Be careful not to lose any of the bolts as they will be reused.

Pull the old thermostat housing gasket seal off of the intake manifold. and replace it with a new gasket.

Pull the old thermostat out of the housing. There are no bolts holding it into place. It simply sits inside of the housing. Pay attention to the orientation of the thermostat and place the new thermostat into the housing in the same manner as the old one.

Bolt the thermostat housing back to the intake manifold using the bolts that were previously removed. Reattach the radiator hose to the thermostat housing by tightening down the band clamp.

Turn the vehicle on and check for leaks where the radiator hose is attached to the Taurus' thermostat housing and where the housing is bolted to the intake manifold. If the hose leaks, simply tighten the band clamp until it stops. If the gasket leaks, you can attempt to tighten the bolts that hold the housing to the intake manifold. In some cases a PVC gasket sealer must be used. Gasket sealer can be purchased at an auto parts store.

Items you will need

  • Phillips screwdriver

  • Replacement thermostat

  • Thermostat gasket

  • Box Wrench

 How to Replace the Thermostat in a 1999 Ford Taurus

Locate the thermostat cover by following the radiator hose that extends from the top of the radiator to the engine intake manifold. The hose connects to the thermostat cover.

Remove the cover by taking the two mounting bolts that hold the cover onto the intake manifold. Pull the cover off of the intake and push it off to the side. You will not have to remove the radiator hose.

Pull the thermostat out of the intake manifold by pulling upward. The thermostat is not bolted into place but may be pressed tightly into the intake manifold. Remove the paper thermostat gasket and discard both items.

Position the new thermostat into the intake manifold and set a new thermostat gasket into place. The thermostat should stay dry in the thermostat housing to prevent damage to the gasket and possible leaking once the Ford is warmed up to operating temperature.

Bolt the thermostat housing back into place with an adjustable wrench and the original mounting bolts.

Turn on the engine and allow it to warm up to normal operating temperature. Check the thermostat cover and the area where the gasket is located for any leaks. If you see leaks, tighten the cover to eliminate them.

Items you will need

  • Replacement thermostat and gasket

  • Wrench

  • Radiator fluid